Understanding the Thermal Runaway Temperature of The Lithium-Ion Battery Testing
Lithium-ion batteries are crucial for powering modern technology, yet they come with safety risks. Research reveals that thermal runaway—a condition where a battery’s temperature rapidly escalates—can initiate at about 70°C (158°F). This phenomenon is responsible for roughly 25% of battery-related failures in devices like smartphones and electric vehicles. To mitigate these risks, it’s vital to pinpoint key temperatures such as self-heating initiation and thermal runaway trigger. Tools like the Large Battery Adiabatic Calorimeter BAC-420AE provide precise measurements of these critical parameters, facilitating the development of safer, more reliable batteries. Mastering the thermal runaway temperature is essential for advancing battery technology and ensuring its safe and effective use.
Definition of Thermal Runaway Temperature in Lithium-Ion Batteries
For lithium-ion batteries, there are three main causes of failure reactions: internal short circuits, high temperature, and overcharging (over-voltage). These factors lead to a rise in temperature, triggering a series of internal chemical reactions that generate heat and gas, potentially causing fire or explosion. This failure reaction is ultimately attributed to temperature, hence termed “thermal runaway.”
Causes of Thermal Runaway
- Internal Short Circuits: Damage or defects within the battery causing unintended electrical pathways.
- High Temperature: Excessive external or internal heat.
- Overcharging (Over-voltage): Charging beyond the battery’s voltage capacity.
Characteristic Temperatures of Thermal Runaway
Thermal runaway has three characteristic temperatures, useful for comparing the thermal safety of different battery types and determining the propagation behavior of thermal runaway:
- Self-heating Initiation Temperature (T1): The temperature at which the temperature rise rate exceeds 0.02°C/min, generally caused by SEI (Solid Electrolyte Interphase) film decomposition.
- Thermal Runaway Trigger Temperature (T2): The temperature at which the temperature rise rate reaches 1°C/s, caused by internal short circuit reactions due to separator damage, lithium plating on the anode, or oxygen release from cathode materials.
- Maximum Temperature (T3): The highest temperature reached during thermal runaway.
Thermal Runaway Process
In an adiabatic environment, after the battery reaches the T1 self-heating temperature, internal side reactions spontaneously occur, slowly releasing heat and gradually heating the battery to temperature T2. The temperature rise further triggers more side reactions. When the temperature reaches T2, a violent chain exothermic reaction occurs, causing a sudden temperature increase. The highest rate of temperature rise at this point reflects the energy release rate during thermal runaway.
Testing Methods for Thermal Runaway Temperature in Lithium-Ion Batteries
Battery Adiabatic Calorimeter
A battery adiabatic calorimeter is commonly used to measure thermal runaway temperatures. This device simulates the adiabatic conditions experienced during actual battery use. Using built-in thermocouple technology, it measures the characteristic temperatures of thermal runaway at the battery’s internal center, enabling the calculation of the total energy released during thermal runaway. This method effectively minimizes the impact of random phenomena on evaluation results, allowing for a quantitative comparison of battery safety.
Contributions to Lithium Battery Development and Design
The battery adiabatic calorimeter aids in various aspects of lithium battery research and development:
- Simulation of Abuse Conditions: Simulates the thermal runaway mechanisms of batteries under abuse conditions, helping researchers predict and optimize battery lifespan.
- Explosion Limit Determination: Determines the conditions under which batteries might explode, optimizing the thermal management performance of vehicle batteries and conducting “temperature shock” tests on power batteries to improve reliability.
- Material Selectionand Decomposition Mechanism Study: On the one hand, assists researchers in selecting suitable electrode materials and electrolytes to enhance battery performance. On the other hand, investigates the decomposition mechanisms of electrode materials, identifying potential issues that may arise during long-term battery use.
- Thermal Stability Evaluation: Evaluates the thermal stability of individual cells and studies thermal stability under different charging states, ensuring safety under various working conditions.
Instrument Recommendation: Large Battery Adiabatic Calorimeter BAC-420AE
Overview of BAC-420AE
The Large Battery Adiabatic Calorimeter BAC-420AE is highly recommended for testing thermal runaway temperatures in lithium-ion batteries. This sophisticated device integrates thermal, electrical, and mechanical abuse methods, supplemented with visible/infrared imaging, gas collection, and specific heat testing functions. Key parameters such as battery specific heat capacity, heat generation during charging/discharging, thermal runaway initiation temperature, maximum thermal runaway rate, and adiabatic temperature rise can be accurately measured.
Applicable Fields
- Battery Pack Testing
- Battery Cell Testing
Key Features and Capabilities
- Simulates Ideal Adiabatic Environment: The BAC-420AE simulates an ideal adiabatic environment, enabling direct measurement of accurate thermal behavior parameters, including thermal runaway onset temperature, maximum rate of temperature rise, and adiabatic temperature rise.
- Comprehensive Data Acquisition: Simultaneous data acquisition of battery voltage, current, temperature, and pressure allows for thorough thermal runaway analysis.
- Integrated Charging and Discharging Module: Features include mode switching, constant current/constant voltage charging settings, charge/discharge current adjustments, and real-time battery capacity calculations.
- High Sensitivity: The device boasts superior self-heating detection sensitivity, capable of detecting minute temperature changes better than the industry standard of 0.02°C/min. This ensures more precise monitoring and recording of the thermal runaway process.
Compliance with Standards
- GB/T 36276-2023
- UL 9540A
- ASTM E198198(2012)
- SN/T 3078.1-2012
- USABC SAND99-0497, July 1999: 3.2 Thermal Stability Tests
- SAE J2464-R2009: 4.4.2 Thermal Stability Tests
- Freedom CAR SAND 2005-3123: 4.1 Thermal Stability
- UL 1973
- GB 38031-2020
Specifications
- Adiabatic Furnace Dimensions: Diameter 420mm, Depth 520mm
- Self-exothermic Detection Sensitivity: Better than 0.02°C/min
- Temperature Difference between Furnace and Sample in Constant Temperature: 0.5°C
- Temperature Control Range: RT to 300°C
- Temperature Tracking Rate: 0.002°C/min to 13°C/min
- Sealed Canister Pressure Range: 0 to 2MPa
- Maximum Needle Travel: Software-settable
- Charge and Discharge Column Overcurrent Capability: -500A to 500A
The BAC-420AE’s advanced capabilities make it an essential tool for researchers and engineers aiming to understand and improve the thermal safety of lithium-ion batteries, providing precise data critical for developing safer and more reliable battery technologies.
In Sum
Understanding the thermal runaway temperature of lithium-ion batteries is essential for ensuring their safety and reliability. This critical phenomenon, influenced by internal short circuits, high temperatures, and overcharging, can lead to severe failures. By pinpointing crucial temperatures such as the self-heating initiation, thermal runaway trigger, and maximum temperature, we can better anticipate and mitigate these risks. Tools like the Large Battery Adiabatic Calorimeter BAC-420AE play a key role in accurately measuring and analyzing these parameters. This expertise not only supports the development of safer batteries but also enhances their performance in various applications, from consumer electronics to electric vehicles. Ultimately, grasping the thermal behavior of lithium-ion batteries is vital for advancing their technology and ensuring their safe and effective use.
